boron nitride grease is a specialty lubricant containing Hexagonal Boron Nitride (h-BN) powder. This line of lubricants helps address new worldwide environmental regulations that minimize/prohibit the use of ingredients that generate phosphorous and sulfur fumes and residues.
Hexagonal boron nitride is a polymorph of boron nitride with interesting properties predisposing it to be used as a lubricant. Its lamellar structure, with alternating layers of boron and nitrogen atoms, results in a strong resistance to chemical attacks. Hexagonal boron lubricants can be applied to surfaces as dry film lubricant, or mixed with water and binders, such as paints, to form lubricity coatings.
When h-BN is added to liquids, it forms an excellent lubricant and offers many advantages over conventional greases and other lubricants. For example, it possesses an extremely low coefficient of friction and resists the corrosion of steel, copper, brass, bronze and cast iron. It also has good thermal stability and good chemical resistance, making it suitable for a wide variety of applications.
Several authors have studied the effectiveness of h-BN in lubricants using various tribological tests on a four ball apparatus, a KEWAT-6 friction machine and a vibration test bench. The results show that a concentration of 10 to 20% of h-BN, depending on the base grease, significantly improves tribological properties compared with those of the base grease.
The research has enabled the identification of the main factors that determine the effectiveness of h-BN as an additive to lubricants. These factors include particle size distribution, morphology, specific surface area and porosity.